Heat pump booster



Filed Jan. 6, 1964 RS3 EQQQQ N m wi INVENTOR ATTORNEY 3,237,422 HEATPUMP BOOSTER Lloyd R. Pugh, Rte. 4, Box 95, Goldsboro, N.C. Filed .lan.6, 1964, Ser. No. 335,963 7 Claims. (Cl. 62-449) The present inventionrelates to heat pumps and more particularly to a heat pump includingfluid flow modulating means for regulating or compensating andincreasing the effective circulating pressures or supply of refrigerantto achieve maximum operating efliciency under varying operatingconditions within the system primarily during the heating cycle uponlarge pressure fluctuations.

The utilization of a reversible refrigerant circuit, commonly referredto as a heat pump, includes an indoor heat exchanger and an outdoor heatexchanger with a reversing valve mechanism within a closed refrigerantcircuit to regulate the direction of refrigerant flow through the closedcircuit under suitable pressure maintained with a fixed refrigerantsupply in the desired direction under a positive head pressure generatedfrom a motoroperated compressor, with control means governing the PatentNo. 2,977,773 may be utilized to incorporate basically the improvementsof this invention whereby increased operating efliciencies may beachieved by the utilization of a capacity booster receiver to augmentthe refrigerant supply in order to compensate for differences duringpressure fluctuations that normally produce pressure drops within thesystem particularly when on the heating cycle at below normaltemperatures when additional capacity isrequired.

The present invention has for one of its main objectives the provisionof an improved heat pump system in which capillary tube flow restrictingmeans and refrigerant control means are incorporated in conjunction witha capacity booster for maintaining the desired operating pressure of aheat pump under below normal operating conditions particularly duringthe heating cycle.

Still another objective of this invention is to provide a heat pump inwhich there is an auxiliary capacity booster containing a receiver forrefrigerant that will supplement the normal charge within a closedcircuit upon increased pressure fluctuations in the system formaintaining a more uniform or constant pressure, within limits, in thesystem particularly when operation is on the heating cycle.

The preferred embodiment of executing the present invention will bedescribed as it relates to the heating cycle since it is during thiscycle that increased refrigerant demand or capacity is required. Thesystem includes a heat pump in which there is an indoor heat exchangerand an outdoor heat exchanger operatively connected within a primaryclosed refrigerant circuit in which circuit a motoroperated compressorwill discharge refrigerant at a pressure range of from 250 pounds persquare inch to 310 pounds per square inch through a discharge line andinto a reversible valve mechanism for reversibly connecting thedischarge line either to the indoor heat exchanger 01' to the outdoorheat exchanger and returnable to the compressor by way of a suction lineand in which suction line a refrigerant receiver or accumulator isprovided.

H Depending upon the positioning of the valve mechanism, refrigerant mayflow either in the direction of a heating cycle or cooling cycledepending upon the utilization to be made of the heat exchangers.Suitable fixed flow heating and cooling capillaries for restrictingrefrigerant flow are supported within the primary closed systemsubstantially adjacent to each of the heat exchangers; the twocapillaries are series-connected in the circuit. The heatice ingcapillary will be by-passed during operation of the heat pump on thecooling cycle so that the cooling capillary provides the desired flowrestriction in the line, while on the heating cycle the coolingcapillary is similarly bypassed. Through this closed circuit, theheating and cooling cycles will produce a high pressure liquidrefrigerant flow between heat exchangers and, depending upon the ambienttemperatures within the zone of the heat exchangers, there will resultcertain pressure differentials. The primary receiver or accumulatorwithin the closed circuit with the various components including thevalve mechanism and the compressor will contain a predeterminedrefrigerant charge dependent upon the normal range of operatingconditions to permit more effective control and regulation therebyreducing large pressure differentials to obtain maximum operatingefliciencies over the normal range of operating conditions. Duringabnormally cold weather conditions additional heating load capacity isrequired, however, the pressure in the closed circuit will dropappreciably. An auxiliary receiver or capacity booster installed in thesystem through a supplementary circuit will supplement the refrigerantsupply in the closed circuit to increase or augment the primary supplyto meet the new demand conditions enabling the system to function withinwider ranges of pressure fluctuations and variations. Fluctuations thatproduce marked pressure differentials will be depressed throughavoidance of excessive starving of refrigerant that will occur in thehigh pressure discharge line during periods of severe weather byintroducing additional refrigerant into the primary circuit from thesupplementary circuit at these periods, of high pressure demand.

Other advantages will become more readily apparent from the accompanyingdrawing in which the diagrammatic presentation of a heat pump circuitembodying the present invention will illustrate the flow of refrigerantin the various circuits and apparatuses that are shown schematically.

In the drawing, the system is illustrated as operating in the heatingcycle only as it is this phase-to which the invention is particularlydirected. The heat pump circuit illustrated includes an indoor heatexchanger or unit 10 utilized in the heating cycle and an outdoor heatexchanger or unit 11 for the cooling cycle in which the outdoor unitgenerally is provided with a larger coil surface area than the indoorheat exchanger coil surface area. Refrigerant, usually Freon 22, underpressure is supplied throughout the primary closed circuit by themotor-operated compressor 12 through the main discharge line 13 from thecompressor which discharge pressure, without limiting this invention forthe purpose of one specific illustration, may be within the range offrom 250 to 310 pounds per square inch, and refrigerant will flow intothe four-way reversing valve mechanism 14. The reversing valve mechanism14, which may be of conventional construction permitting dischargeeither to the outdoor or indoor heat exchangers, is provided with asuitable slide gate to direct the How of refrigerant to the indoor heatexchanger 10 through the line 16 as is illustrated during the heatingcycle position.

During normal heating cycle operation, the liquid refrigerant will flowunder pressure through the indoor unit coil and into the high pressureliquid refrigerant line 17. A cooling cycle capillary tube 18 isinstalled in the high pressure line 17 with inlet and dischargepositions spaced from each other so as to straddle the check valve 19.During the heating cycle, liquid refrigerant will flow through the checkvalve 19 in its path of flow to the heating cycle capillary tube 20'with inlet and discharge openings spaced apart so as to starddle thecheck valve 21 in the pressure line 17. Liquid refrigerant flowingthrough the line 17 in the direction of the outdoor heat exchanger 11will not pass through the check valve 21 but will pass through thecapillary tube 20 which will be in close proximity to the outdoor unitthat will be used as the evaporator. The refrigerant will return fromthe outlet of the outside heat exchanger through line 22 to the valvemechanism 14 and pass through the valve gate 15 into the suction line23, the lower end of which is provided with an accumulator 24 at thebottom of which is an oil reservoir and an overflow oil return line 25that communicates with the suction return line 26 leading to thecompressor 12.

The closed circuit containing the desired supply of refrigerantincluding an additional quantity contained within the accumulator 24 isgenerally adequate during heating and cooling cycles for a given systemunder normal operating conditions with reasonable temperaturefluctuations to maintain the desired supply of refrigerant Within thesystem. However, the heating cycle requires additional refrigerantduring extended or abnormally low temperature conditions at which timethe pressure of the refrigerant within the closed system decreasesappreciably. It will be readily apparent that during the cooling cycle,the valve gate 15 may be shifted to the right changing the course offlow of the refrigerant whereby the refrigerant under pressure will passfrom the line 13 through the valve 14 into the line 22 leading to theoutside heat exchanger. The liquid refrigerant will pass through thecheck valve 21 in the pressure line 17 bypassing the capillary tube 20and will pass through the cooling capillary tube 18 leading to theindoor heat exchanger with the refrigerant ultimately returning throughline 16 to the suction line 23 on its return to the compressor 12.

A supplementary or auxiliary circuit for refrigerant is interconnectedwith the primary closed circuit to supply or remove refrigerant inaccordance with predetermined pressure conditions in the refrigerant. Anauxiliary receiver or capacitor booster 27 containing a supply ofrefrigerant is connected to the high pressure refrigerant line 17 bymeans of line 28 which may be suitable tubing. The receiver or capacitybooster 27 is also connected to the suction line 23 by the line 29 whichmay be made of tubing.

A solenoid valve 30 is installed in the line 28 and a solenoid valve 31is installed in the line 29. A pressure- 1 operated switch 32 iselectrically connected to solenoid valve 31 and a refrigerant pressuretube 33 is connected at one end to the discharge line 13 and at theother end to switch 32 for conveying refrigerant pressure in thedischarge line to the switch 32 which will operate between predeterminedpressure limits. In one preferred installation, the switch 32, which maybe a high pressure switch available commercially as a Penn 27AP20, mayhave a cut-out pressure of 260 pounds per square inch and a cutinpressure of 240 pounds per square inch. The switch 34 for actuatingsolenoid 30 is of the same type as switch 32 but is provided with acut-in setting of 310 pounds per square inch and a cut-out setting of280 pounds per Square inch with the line or tubing 35 connected at oneend to the switch and at the other end to the high pres sure dischargeline 13. The individual solenoid valves 30 and 31 suitable forinstallation are available as Al-co solenoid valves 5102-2.

Line current of 220 volts may be supplied to the switches 32 and 34 andto the solenoid valves 30' and 31 through the conductors 35 and 36. Thewiring diagram included in the drawing presents the common conductor 35to both switches 32 and 34 with the line 36 being connected to thesolenoid valves directly or through a jumper line 37. The switch-valvereturn lines 38 connect the valve 31 with the switch 32 and line 39connects valve 30 to switch 34.

The utilization of the capacity booster or receiver 27 within theauxiliary or supplementary circuit will permit the head pressure to bevaried, modulated or compensated for by the switch and valve settingcontrols so that when pressure builds up to 310 pounds per square inch,the solenoid valve 30 will open while solenoid valve 31 will remainclosed permitting liquid refrigerant in line 17 to flow into thecapacity booster 27 through the line 28. When the overall pressure inthe system drops to approximately 280 pounds per square inch in the line13, the solenoid valve 30 will close and solenoid valve 31, which isnormally closed, will remain closed thereby storing the liquidrefrigerant in the capacity booster 27. The head pressure will thenremain between the selected range of from approximately 280 pounds to310 pounds per square inch. Depending upon the high pressure cutout, theswitch will not trip out on high pressure as it is set sufi'icientlyhigh to avoid being tripped out except a safety switch may be employedin the line which will kick out in the event the head pressure builds uprapidly such as when there is a malfunction in the system or when a fanbelt breaks.

In extremely severe cold weather, additional refrigerant supply isrequired in order to maintain the elevated head pressure in the systemso as to deliver an adequate quantity or supply of energy to the spacebeing heated by the indoor heat exchanger 10. When the head pressure inthe dis-charge line drops to 240 pounds per square inch, switch 32 willactuate the solenoid valve 31 to open it while the solenoid valve 30remains in the closed position. Refrigerant in the capacity booster 27will be introduced and supplied into the system through the line 29 thatleads to the suction line 23 that passes to the compressor 12.Sufficient refrigerant will be supplied through the line 29 from thecapacity booster 27 until the head pressure builds up from 240 to 260 or2-80 pounds per square inch. With the additional refrigerant suppliedinto the primary system from the auxiliary closed circuit, additionalrefrigerant contained within the primary circuit will result inadditional heat pick-up in the coil 11 which will ultimately bedischarged into the area to be heated through the indoor heat exchanger10.

The utilization of the capacity booster in the system Will permit thehead pressure during the heating cycle to be maintained in operatingcondition at maximum pressure levels. When frost is generated on theoutside heat exchanger coil, the valve mechanism 14 will usually go intothe cooling cycle at which time the outside fan (not shown) utilizedwith the outside heat exchanger will cut-out by means of another control(not shown) from another source which when actuated defrosting isinitiated as more refrigerant is fed through the system. Additionalrefrigerant supplied from the auxiliary to the primary system willpermit increased internal heat pick-up with the valve 31 being open tosupply the additional refrigerant charge to the system therebyaccelerating the defrost cycle from the usual period of ten minutes downto a period of from three to five minutes.

It will be readily apparent that modifications and variations may bemade in the types of valves and electrical controls for the valves topermit the introduction of the additional refrigerant into the systemfrom the capacity booster by incorporating spring-loaded pressure valvespre-set within the desired pressure range to open and close, however,the system described above is preferred as it requires a minimum ofmaintenance. It may also be desirable to incorporate check valves in thelines 28 and 29 without deviating from the purpose and spirit of thisinvention and such modifications are contemplated within the scope ofthe appended claims.

What is claimed is:

1. A heat pump comprising a reversible closed refrigerant circuitincluding an indoor heat exchanger, an outdoor heat exchanger, means insaid circuit including a compressor having a discharge line and asuction line and reversing valve means for reversibly connecting saiddischarge and suction lines to said heat exchangers for effecting flowof refrigerant through said circuit in either direction whereby saidpump may be operated on a cooling cycle with the outdoor heat exchangerfunctioning as a condenser and receiving high pressure refrigerant fromsaid compressor or on a heating cycle with the indoor heat exchangerfunctioning as a condenser and receiving high pressure refrigerant fromsaid compressor, flow restricting means in said circuit for controllingthe flow of refrigerant from either of said heat exchangers to the otherand for maintaining a pressure difference between said heat exchangers,said flow restricting means comprising a cooling capillary connected inseries to said indoor heat exchanger and a heating capillary connectedin series to said outdoor heat exchanger, a conduit connecting saidcapillaries in series, and means for by-passing one or the other of saidcapillaries whereby the pressure difference between said heat exchangersis provided by said cooling capillary during operation of said pump onthe cooling cycle and by said heating capillary during operation of saidpump on the heating cycle so that said conduit conducts high pressurerefrigerant during either cycle of operation, and a refrigerant capacitybooster means for augmenting refrigerant supply and refrigerant pressurecirculating in said circuit, said booster means comprising a receiverhaving a supply of refrigerant therein, a supplementary circuitconnecting said receiver to said capillary-connecting conduit and to thecompressor suction line pressure responsive valve means in saidsupplementary circuit selectively operable between limits to supplyrefrigerant to said closed refrigerant circuit upon reduction ofrefrigerant pressure in said closed circuit or to remove refrigerantfrom said closed circuit upon increase of refrigerant pressure.

2. A heat pump as claimed in claim 1 and wherein said pressureresponsive valve means comprises solenoid valves in the supplementarycircuit, each of said solenoid valves having refrigerant pressureactuating means for energizing said valves at predetermined pressurelimits to open or close said valves.

3. A heat pump as claimed in claim 2 and wherein said refrigerantpressure actuating means has a line connected to said discharge line totransmit refrigerant pressure.

4. A heat pump as claimed in claim 1 and wherein said pressureresponsive valve means comprises a first solenoid valve operative toopen between a first set of pressure conditions to admit refrigerantinto said booster from said closed circuit and a second solenoid valveoperative to open between a second set of pressure conditions to supplyrefrigerant to the closed circuit.

5. A heat pump comprising a reversible closed refrigerant circuitincluding an indoor heat exchanger, an outdoor heat exchanger, means insaid circuit including a compressor having a discharge line and asuction line and reversing valve means for reversibly connecting saiddischarge and suction lines to said heat exchangers for effecting a flowof refrigerant through said circuit in either direction whereby saidpump may be operated on a cooling cycle with the outdoor heat exchangerfunctioning as a condenser and receiving high pressure refrigerant fromsaid compressor or on a heating cycle with the indoor heat exchangerfunctioning as a condenser and receiving high pressure refrigerant fromsaid compressor, flow restricting means in said circuit for controllingthe flow of refrigerant from either of said heat exchangers to the otherand for maintaining a pressure difference between said heat exchangers,said flow restricting means comprising a cooling capillary connected inseries to said indoor heat exchanger and a heating capillary connectedin series to said outdoor heat exchanger, a conduit connecting saidcapillaries in series, and means for by-passing one or the other of saidcapillaries whereby the pressure difference between said heat exchangersis provided by said cooling capillary during operation of said pump onthe cooling cycle and by said heating capillary during operation of saidpump on the heating cycle so that said conduit conducts high pressurerefrigerant during either cycle of operation, and a refrigerant capacitybooster means for augmenting the refrigerant supply and pressurecirculating in said circuit, said booster means comprising a receiverhaving a supply of refrigerant therein, an auxiliary circuit connectingsaid receiver to said capillaryconnecting conduit and to the compressorsuction line, electrically operated pressure responsive valve means insaid supplementary circuit selectively operable automatically betweenlimits to supply refrigerant to said closed refrigerant circuit uponreduction of rerfrigerant pressure in said closed circuit or to removerefrigerant from said closed circuit upon increase of regfrigerantpressure.

6. A heat pump as claimed in claim 5 in which said pressure responsivevalve means comprises a first pressure actuated electrically energizedsolenoid valve operative to open only between a first set of pressureconditions to admit refrigerant into said capacity booster and a secondpressure actuated electrically energized solenoid valve operative toopen only between a second set of pressure conditions to removerefrigerant into said closed circuit suction line, said first valvebeing closed when said second valve is open and vice-versa.

7 A heat pump as claimed in claim 5 and wherein said pressure responsivevalve means includes a pair of solenoid operated pressure operatedvalves, one of said valves being operative to admit refrigerant to saidbooster from said conduit and another of said valves being operative toadmit refrigerant from the booster to the suction line of the closedcircuit.

References Cited by the Examiner UNITED STATES PATENTS 2,715,317 8/1955Rhodes 62149 3,065,610 11/1962 Maudlin 62- 149 3,153,913 10/1964 Brody62--174 X MEYER PERLIN, Primary Examiner.

1. A HEAT PUMP COMPRISING A REVERSIBLE CLOSED REFRIGERANT CIRCUITINCLUDING AN INDOOR HEAT EXCHANGER, AN OUTDOOR HEAT EXCHANGER, MEANS INSAID CIRCUIT INCLUDING A COMPRESSOR HAVING A DISCHARGE LINE AND ASUCTION LINE AND REVERSING VALVE MEANS FOR REVERSIBLY CONNECTING SAIDDISCHARGE AND SUCTION LINES TO SAID CIRCUIT IN EITHER EFFECTING FLOW OFREFRIGERANT THROUGH SAID CIRCUIT IN EITHER DIRECTION WHEREBY SAID PUMPMAY BE OPERATED ON A COOLING CYCLE WITH THE OUTDOOR HEAT EXCHANGERFUNCTIONING AS A CONDENSER AND RECEIVING HIGH PRESSURE REFRIGERANT FROMSAID COMPRESSOR OR ON A HEATING CYCLE WITH THE INDOOR HEAT EXCHANGERFUNCTIONING AS A CONDENSER AND RECEIVING HIGH PRESSURE REFRIGERANT FROMSAID COMPRESSOR, FLOW RESTRICTING MEANS IN SAID CIRCUIT FOR CONTROLLINGTHE FLOW OF REFRIGERANT FROM EITHER OF SAID HEAT EXCHANGERS TO THE OTHERAND FOR MAINTAINING A PRESSURE DIFFERENCE BETWEEN SAID HEAT EXCHANGERS,SAID FLOW RESTRICTING MEANS COMPRISING A COOLING CAPILLARY CONNECTED INSERIES TO SAID INDOOR HEAT EXCHANGER AND A HEATING CAPILLARY CONNECTEDIN SERIES TO SAID OUTDOOR HEAT EXCHANGER, A CONDUIT CONNECTING SAIDCAPILLARIES IN SERIES, AND MEANS FOR-PASSING ONE OR THE OTHER OF SAIDCAPILLARIES WHEREBY THE PRESSURE DIFFERENCE BETWEEN SAID HEAT EXCHANGERSIS PROVIDED BY SAID COOLING CAPILLARY DURING OPERATION OF SAID PUMP ONTHE COOLING CYCLE AND BY SAID HEATING CAPILLARY DURING OPERATION OF SAIDPUMP ON THE HEATING CYCLE SO THAT SAID CONDUIT CONDUCTS HIGH PRESSUREREFRIGERANT CAPACITY BOOSTER CYCLE OF OPERATION, AND A REFRIGERANTDURING EITHER MEANS FOR AUGMENTING REFRIGERANT SUPPLY AND REFRIGERANTPRESSURE CIRCULATING IN SAID CIRCUIT, SAID BOOSTER MEANS COMPRISING ARECEIVER HAVING A SUPPLY OF REFRIGERANT THEREIN, A SUPPLEMENTARY CIRCUITCONNECTING SAID RECEIVER TO SAID CAPILLARY-CONNECTING CONDUIT AND TO THECOMPRESSOR SUCTION LINE PRESSURE RESPONSIVE VALVE MEANS IN SAIDSUPPLEMENTARY CIRCUIT SELECTIVELY OPERABLE BETWEEN LIMITS TO SUPPLYREFRIGERANT TO SAID CLOSED REFRIGERANT CIRCUIT UPON REDUCTION OFREFRIGERANT PRESSURE IN SAID CLOSED CIRCUIT OR TO REMOVE REFRIGERANTFROM SAID CLOSED CIRCUIT UPON INCREASE OF REFRIGERANT PRESSURE.